Polyphase circuit interrupter of the fluid blast puffer-type

ABSTRACT

A polyphase puffer-type circuit interrupter with a plurality of pole units in which a blast of gas is generated within a puffer mechanism to extinguish the established arc. The gas under pressure flows out of a blast orifice and escapes in a downstream compartment. All downstream compartments of the different pole units communicate with each other so as to increase the flow of the blast gas.

United States Patent Ferton et al.

3,641,295 Feb. 8, 1972 [54] POLYPHASE CIRCUIT INTERRUPTER FOREIGN PATENTS OR APPLICATIONS OF THE FLUID BLAST PUFFER'TYPE 537,482 6/1941 Great Britain ..200/148 A 72 Inventors: JeabYves m Jacques Hennebert; 384,673 2/1965 Switzerland ..200/148 A Francois Stnppoh, all of Grenoble, France Primary Examiner-Robert S- Macon [73] Assignee: Merlin Gerin, Societe Anonyme, Grenoble, Attorney-Stevens, Davis, Miller & Mosher France 57 ABSTRACT [22] Filed: June 30, 1970 1 A polyphase puffer-type circuit interrupter with a plurality of [2]] Appl' 51,313 pole units in which a blast of gas is generated within a pufier mechanism to extinguish the established arc. The gas under pressure flows out of a blast orifice and escapes in a [52] US. Cl ..200/148 A, 200/ 1506 downstream compartment A downstream compartments of [51] Int. Cl. ..Hll1 33/88 58 Field f h 200 148 A 150 G the different pole units communicate with each other so as to o Searc increasetheflowofthe blastgm [56] References Cited 14 Claims, 9 Drawing Figures UNITED STATES PATENTS 3,381,101 4/1968 Strom etal ..200/148A I i I" IE: I 1 1 b l I 51 I l I to :l: I I s7- i l I I 26 z l l 3 It I a 47- l}! l l l I! l l l i I l i r 1 1 I I i l l i i 1 r l I i l P 46-" 1 Q i i 28 F I PAIENIEBFEB 8 1972 3.641.295

SHEET1UF6 32 INVENTORS JEAN- YVES FERTON JACQUES HENNEBERT FRANCOIS STRIPPOLI QJWM I PATENTEU FEB 8 I972 SHEET 2 [1F 6 POLYPHASE CIRCUIT INTERRUPT ER OF THE FLUID BLAST PUFFER-TYPE The present invention relates to a polyphase circuit interrupter with pumped gas blast having a plurality of pole units arranged alongside of each other, each pole unit comprising an elongated enclosure containing an isolation and arc-extinguishing fluid and subdivided into at least two compartments, a blast orifice providing communication between the said two compartments located upstream and downstream of the said orifice with respect to the direction of flow of the blasting fluid.

Circuit interrupters of this type are known which employ as quenching fluid air or a special gas, such as sulfur hexafluoride (SI- contained in an enclosure common to the different poles of the circuit interrupter. In order to reduce the space taken up by these apparatus, greater and greater use is being made of individually closed airtight poles, each containing the volume of gas necessary for its proper operation. In order to create the blasting, a piston cooperates with a cylinder in such a manner as to produce, by displacement of the piston or of the cylinder, a flow of gas in a nozzle or other orifice which provides communication between the inside of the cylinder and another space. This flow, upon the opening of the contacts, causes a blasting of the are through the nozzle and this are is then rapidly quenched. Circuit interrupters with a pressure remove or reduction have been proposed but, in practice, a pressure is generally created in the compartment of variable volume, referred to as the upstream compartment," which results in a flow through the nozzle in the direction towards the other compartment of constant or increasing volume, which is known as the downstream compartment."

The performance of such a circuit interrupter depends on the quantity and rate of flow of the quenching gases through the nozzle, which in their turn are a function of the differential pressure at the nozzle. The transfer of the gas from one compartment to the other produces greater variations in pressure the larger the volume transferred as compared with the volume of the compartment, and it will be understood that any increase in the volume of the downstream compartment collecting the gas at the emergence from the nozzle will favor the flow and the blasting.

The object of the present invention is to increase the available downstream volume for a given overall size of the circuit interrupter so as to reinforce the arc blasting effect.

The circuit interrupter in accordance with the invention is characterized by the fact that it comprises an intercommunication system which causes all of said compartments located on the same side, upstream or downstream, of the said blast orifices of the different poles to communicate with each other so as to increase the flow of the blast fluid.

In the case of a compression circuit interrupter, the downstream compartments of the different poles communicate with each other so as to permit a transfer of gas from one pole towards another upon a lack of equilibrium of the pressures. If the defect to be eliminated affects only one of the phases, the volume available for the expansion of the gases of the active pole which cuts the defect is substantially increased as compared with the conventional apparatus by the use of the cold volumes of the other poles which are practically inactive.

When the apparatus interrupts a large current on the three phases, there is also advantageous, as compared with the known apparatus, the fact that at a given moment the instantaneous values of the current of the different phases and the instantaneous pressures resulting therefrom differ from one phase to the other. Furthermore, when the first phase has been interrupted, the second and third phases which are then interrupted benefit from the downstream volume of the first phase which is then relatively cold," since the first phase has been interrupted within a very short period of time.

It is obvious that the invention can also be applied to a polyphase circuit interrupter with a pressure reduction. ln this case the upstream compartments are connected together.

The communicating conduits between the poles preferably have a substantial cross section which limits the losses in head. and they can connect the compartments in question of the poles at a given place in front of or behind the poles, below or directly between the poles, etc.

The puffer gas blast mechanism can be any desiredfor instance one with movable pumping piston and stationary cylinder, the piston being arranged above or below the nozzle; one with stationary piston and movable cylinder, at bellowstype mechanism, etc.

Furthermore, the nozzle may be movable or stationary and in certain cases may assume the shape of a simple orifice or be formed of the hollow moving contact itself.

With the same purpose in view, namely of increasing the flow of the extinguishing gas by increasing the volume collecting the gas escaping from the nozzle, in the case of a pressure system, the present invention is directed at using all the dead" or available spaces of the enclosures of the circuit interrupter. In circuit interrupters of the type indicated, the moving unit is actuated by a rod which emerges from the enclosure and serves as current lead to the contacts. The insulation of the rod may then advantageously be effected by an insulating section of the rod, located within the enclosure of the circuit interrupter in an insulating atmosphere, for instance of sulfur hexafluoride, which permits a substantial decrease in the insulation stresses. The picking up of the current on the rod is effected in front of the insulating section and the space of the enclosure containing these pickup and insulating portions constitutes in the known devices a dead space the gases of which do not contribute to the extinguishing of the are.

In accordance with the invention, communicating means provide communication between the said downstream compartment and the dead space or third compartment of the enclosure in such a manner as to increase the volume located downstream of the gas flow orifice.

The communication can advantageously be brought about by the hollow contact rod whose wall is provided for this purpose with an orifice in the'region of the said third compartment.

Another object of the present invention is to permit the production of a circuit interrupter of the type indicated which enjoys complete tightness.

The use of special gases, such as sulfur hexafluoride, requires very severe conditions of airtightness which are all the more difficult to satisfy the higher the number of communicating lines or connections.

The polyphase circuit interrupter comprises in accordance with the invention a housing of synthetic material which is common to different poles and which defines and surrounds the said elongated enclosures of the poles and within which the said intercommunication system for the compartments of the different poles extends. The said housing may consist of a monoblock molding with internal subdivisions providing recesses which receive the different poles and the said system of intercommunication between the compartments of different poles.

Still another object of the present invention is to provide a circuit interrupter with housing of molded plastic which is of strong structure capable of withstanding substantial internal pressures. For this purpose, transverse webs bracing the housing of the circuit interrupter extend between the openings or recesses of the different poles. The communicating conduits between the different compartments may be included in or formed of discontinuities in these webs. Molding processes permit the manufacture of parts of elaborate shape and the molding of the housing or body of the circuit interrupter in accordance with the invention is effected without difficulty.

Still another object of the invention is to obtain a circuit interrupter of increased performance qualities, low cost of manufacture and easy assembly.

The circuit interrupter in accordance with the invention comprises blast compartments of variable volume of each pole which are formed of attached parts fastened to the inside of the said plastic housing and compartments common to the different enclosures of the poles or in direct communication between them confined by the said housing.

It will be even clearer from the illustrative embodiment described in detail below that the manufacture of such a circuit interrupter is substantially simplified.

Other advantages and characteristics of the present invention will become evident from the following description of one of the embodiments of the invention given solely by way of illustration and shown in the accompanying drawings in which:

FIG. 1 is a partially broken away perspective view of a molded plastic housing or body of a polyphase circuit interrupter in accordance with the invention;

FIG. 2 is a transverseaxial section on a larger scale of the circuit interrupter of the invention, the housing of which has been shown in FIG. 1;

FIG. 3 is an elevation, partially in section along the line III III, of the circuit interrupter of FIG. 2;

FIG. 4 is a section along the line IV-IV of FIG. 2;

FIG. 5 is an elevation, partially in axial section, ofa circuit interrupter in accordance with a variant embodiment of the invention;

FIG. 6 is a view similar to that of FIG. 2 illustrating another variant of the invention;

FIG. 7 is a section along the line VII-VII of FIG. 6.

FIG. 8 is a section along the line VIII-VIII of FIG. 6;

FIG. 9 is a view similar to that of FIG. 4 further illustrating another embodiment of the invention.

In FIGS. 1 to 4, a three-pole circuit interrupter or breaker comprises a housing 10 of plastic material, such as an epoxy resin, constituting the body of the circuit breaker. This housing comprises essentially three enclosures 12, 14 and 16 forming cutout chambers or are extinction chambers which are tub'ular and each of which contains one pole ofa puffer-type circuit interrupter, such as an isolating switch which cuts out under load or a circuit breaker. The current cutout members of one chamber are represented schematically in FIGS. 2 and 3, it being understood that for the application of the invention their nature and arrangement may differ and may be based on a different puffer fluid blast principle than the one which has been shown. In the example selected the circuit interrupter is of the pressure type with movable nozzle, but the invention can also be applied to a circuit interrupter of the pressure reduction type with stationary nozzle having two moving contacts, main contacts and spark-arresting contacts and the like.

The housing 10 has two protuberances per pole constituting insulated passage housings 18, 20 (in the case of chamber 12), 22, 24 (in the case of chamber 14) and 26, 28 (in the case of chamber 16). The poles which are housed respectively in the enclosures 12, 14 and 16 are all identical and therefore only one of them, visible in FIGS. 2 and 3, will be described in detail below. Each passage 18 and 20 comprises a cylindrical conductor, such as 30 and 32, terminating on the one side in a fastening area of a plug-in terminal 34 and 36 or some other contact member (not shown in FIG. 3). At the other inside end of the body 10, the current lead or outlet conductor 30 bears an intermediate current pickup contact 38, represented schematically generally as of the sliding or rubbing contact type which cooperates with a moving cylindrical contact rod 40. The intermediate contact 38 is advantageously fastened to the end of the conductor 30 via a screw 42 and washer 43 for a purpose which will be explained below.

The other current outlet or feed conductor 32, incorporated in the housing 10, terminates in a connection 44 which emerges from the housing 10 and receives by threading a stationary contact 46 establishing electrical continuity between the conductor 32 and said contact 46. A stationary transverse partition 47 embedded in the wall of the enclosure 12, for instance by means of circlips, defines two spaces, one of which forms the arc extinction chamber proper and the other a dead space 49 for housing the intermediate contact 38 and an insulating section 51 interposed in the moving contact rod 40. The compartment 49 is closed off by a cover 54, either individual or common to the three enclosures l2, l4 and 16, and

' fastened in any desired manner to the molded body 10 of the circuit interrupter. The actuating rod of the moving contact 40 passes through the cover 54 through an opening which is extended by a cylindrical guide 58 which cooperates with a guide collar 60 on the rod 40. A diaphragm or bellows 62, fastened in airtight manner to the cover 54 and the rod 40 respectively, assures the tightness of the compartment 49 while permitting a reciprocating linear movement of actuation of the moving contact 40 from the outside of the body of the circuit interrupter by any desired device (not shown). The cover 54 hermetically closes off the housing 10 and the closed spaces or enclosures l2, l4 and 16 contain a compressed gas of high cutout and isolating power, such as sulfur hexafluoride (SF By placing the insulating section 51 of the rod 40 within the compartment 49 in a sulfur hexafluoride atmosphere, the isolation stresses are substantially reduced.

The moving contact rod 40 passes through the stationary partition 47 and penetrates into the arc extinction chamber which is divided into two compartment 53 and 55 by a moving blowout piston 48 rigidly connected with the rod 40. The piston 48 bears a blowout nozzle 50 which provides communication between the upstream compartment 53, defined by the piston 48 and the stationary transverse partition 47, and the downstream compartment 55 on the opposite side of the piston 48, the expressions upstream and downstream" being defined with respect to the direction of flow of the gas through the nozzle 50 during the opening of the circuit breaker.

The peripheral surface of the piston 48 slides in direct contact with the smooth cylindrical inner wall of the housing 12 via a joint 52. The tightness obtained by this joint does not need to be perfect, and one can tolerate slight imperfections in the inner wall of the housings l2, 14, 16 without the blasting being seriously affected thereby, in view of the high speed of displacement of the piston 48 during the extinction of an arc.

The rod 40 terminates in a contact surface which abuts against the stationary contact 46 in closed position of the circuit breaker in a zone confined by the nozzle 50, advantageously at the place of a neck of restricted cross section. The moving contact rod 40 is hollowed in its portion within the enclosure 12 and orifices 57 provide communication between the hollow inside of the contact 40 and the compartment 49. Upon the opening of the contacts 40, 46, a part of the blowout gases can thus escape through the hollow movable contact 40 and the orifices 57 towards the compartment 49.

The downstream compartment 55 of the different poles contained in the enclosures 12, 14 and 16 communicate with each other via passages provided in the housing 10 itself.

The circuit breaker in accordance with the invention operates in the following manner:

In closed position of the circuit breaker, as shown in FIGS. 2 and 3, the contacts 40 and 46 of the different poles 12, 14 and 16 are closed and abutting and the pressure of the compressed gas is equalized in all the compartments 49, 53 and 55 of the different-enclosures due to the communications 70 and the hollow contacts 40. Upward displacement, as indicated by the arrow in FIG. 2, of the rods 40 for the opening of the circuit breaker is caused to take place simultaneously, preferably, for all the poles by any suitable device (not shown). The are established upon the opening of the contacts 40 and 46 is subjected to intensive blowing in the nozzle 50 due to the flow of the gas expelled from the upstream compartment 53 by the displacement of the piston 48 carried along by the moving contact 40. The extinguishing gas escapes on the one hand through the hollow contact 40 and the orifice 57 into the compartment 49 and on the other hand into the downstream compartment 55.

In the case of a defect in a single phase, for instance that corresponding to the pole 12 of the circuit interrupter, the pressure produced in the compartment 55 on the one hand by the flow of the blast gas through the nozzle 50 and on the other hand by the heating of the gases under the action of the arc exceeds that prevailing in the compartments 55 of the adjacent poles the heating of which has been less. A transfer of fluid towards the latter compartments is effected through the passages 70 in the direction indicated by arrows in FIGS. 3 and 4. The blowing in the nozzle 50 of the pole 12 is reinforced thereby and the extinguishing ofthe arc is accelerated.

In the case ofa three-phase defect, the cutting out of the different poles takes place successively after a period of time sufficient for the partial cooling of the gases of the adjacent poles which cut out previously. A transfer of gas between the different poles therefore also takes place and increases the blowing of extinguishing gases.

The utilization of the dead spaces in accordance with the invention is advantageously employed in combination with the intercommunication of the downstream volumes of the different poles in the manner described above, but it is obvious that the said downstream volumes may comprise only compartments 55 or on the other hand any other space located downstream of the blast nozzle.

In order to manufacture the housing 10, the conductors 30, 32, the connectors 44 and the different cores are placed in a mold. After pouring and polymerization, one then obtains the housing as shown in FIG. 1. The fixed contacts 46 are then screwed into the connections 44, whereupon the moving units 40, 48, 50 are introduced into their chambers. The partition 47 and the intermediate contacts 38 and the cover 54 are then put in position and the enclosure is filled with a compressed gas in suitable fashion. The assembling as well as subsequent disassembling are therefore particularly easy and do not require any special machining.

The invention is, of course, in no way limited to the embodiment which has been more particularly described by way of example and shown in FIGS. 1 to 4.

FIG. 5 shows a three-pole circuit interrupter in accordance with a variant of the invention having separate poles 72, 74 and 76 the tubular enclosures of which formed of insulating material are attached to a common support 78. The intercommunication conduits of the downstream compartments of the different poles 72, 74 and 76 can be incorporated or formed by the common support 78. The operation of the circuit interrupter is not modified by this subdivision of the housing into independent elements. In the example shown in FIG. 5 the internal structure of the poles 72, 74 and 76, only one of which, 72, will be described subsequently, since the others, 74 and 76, are identical, differs from that illustrated in FIG. 3 so as to permit a transfer of the control of the side of the downstream compartment and include this control possibly in the support 78. For this purpose, the pole 72 comprises a tubular insulating envelope 80 closed at one of its ends and connected hermetically at its other end to the reservoir 78, possibly made of metal, which forms a common support structure for the different poles. The reservoir 78 and the envelopes or enclosures 72, 74 and 76 communicate with each other and contain a compressed gas, such as sulfur hexafluoride (SF The blind end of the enclosure 72 bears a coaxial fixed contact 81 connected to a passage conductor or any other electrical connecting area. The stationary contact 81 cooperates with a hollow moving contact 82 which is capable of sliding in the enclosure 72 under the action of a control rod which forms an extension of it and is rigidly connected to a system of levers 84 for converting a rotary movement of a shaft 86 into a linear reciprocating movement of the moving contact 82. The control shaft 86 which is common to the three poles 72, 74 and 76 extends within the reservoir 78 so as to limit the hermetic passages. The moving contact 82 is insulated from the control rod which forms an extension of it by an insulating section 88. A passage conductor 90 cooperates with the moving contact and picks up the current in a manner similar to that described above.

A stationary transverse partition 92 divides the enclosure 72 into two closed compartments 94 and 96, referred to respectively as the downstream compartment 94 and the upstream compartment 96. A stationary nozzle 98 of insulating or resistant material and having a convergent-divergent shape is arranged on the partition 92 which has a central opening for the passage of the fixed contact 81 and to permit the blowing. The neck of the nozzle surrounds the end of the moving contact 82 with a small amount of play.

The partition 92 is also pierced to permit the passage of a suitable number-for instance fourof sliding control rods 100 which are hollow and which can be arranged in the form of a squirrel cage. The lower ends of the hollow rods 100 are rigidly connected with the moving contact 82 by a disc, for instance star shaped, 102. Their upper ends are rigidly connected with a blow piston 104 through which they pass. The piston 104 which is pierced to permit the passage of the stationary contact 81 is thus rigidly connected with the moving contact 82 in the example selected, but it will be understood that a dead-stroke drive mechanism can also control the piston 104 from the movement of the moving contact 82, or vice versa. The piston 104 which slides directly on the inner wall of the envelope 72 defines in the upstream compartment 96 compression volume upstream of the nozzle 98. The moving contact 82 is hollow and perforated at 106 to cause its inside to communicate with the compartment 94.

This device operates in the following manner:

In the closed position shown, the current passes through the abutting contacts 81 and 82. In order to open the apparatus, the shaft 86 is actuated and it, by means of the system of levers 84, displaces the moving contact 82 carrying along the disc 102, the hollow rods 100 and the piston 104. The gases. present in the compression volume are compressed by the piston 104 and pass through the nozzle 98 to penetrate into the hollow moving contact 82. These gases then pass through the holes 106 to arrive in the downstream compartment 94. At the same time, a part of the gases delivered into the downstream compartment 94 passes through the hollow rods 100 and enters into the space behind the piston 104. One thus obtains a true circulation of the gas, resulting in a considerably increase in the blowing.

It is easy to see that the entire enclosure 72 is utilized for the blowing of the arc and that a transfer of fluid from a charged pole towards a less charged adjacent pole is effected automatically through the enclosure 78. The volume of the reservoir 78 contributes to the circulation of the gas and to its cooling. Upon the withdrawal of the moving contact 82 from the nozzle 98, the compressed gas escapes in part into the downstream compartment 94 without passing through the connection of the hollow contact 82. The stationary contact 81 can also be hollow and assure communication between the spaces located on opposite sides of the piston 104, which avoids the use of hollow rods 100. The apparatus of FIG. 5 has extensive analogies to the one illustrated in FIGS. 1 and 4 and a more detailed description of its structure and operation would appear superfluous.

In accordance with another embodiment of the invention, shown in FIG. 9, which is a view similar to that of FIG. 4, and in which the same reference numbers are used to designate similar or identical parts, the apparatus in accordance with FIGS. 1 to 4 is modified so as to have an outer parallelepiped contour which facilitates the attachment thereof. Inner transverse webs 110 and 112 separate the adjacent enclosures 12, 14 and 14, 16 respectively and constitute braces or ribs which reinforce the structure of the molded body 10. The square outer section with circular recesses 12, 14 and 16 liberates in the corner portions spaces used for the housing of the channels 114, 1 16, 118 and extending on the inside of the webs 110 and 112 and causing the downstream compartment 55 (see FIG. 2) to communicate via orifices 119 with the dead compartment 49. The channels 114 to 120 can be common to the adjacent enclosures or be individual to each enclosure. They may be associated with the communication by the hollow contact 40 and on the other hand take the place of the latter, permitting the use of a solid moving contact. The making of the channels upon the molding does not present any difficulty whether they are made in the mass or produced by inserts. The apparatus in accordance with FIG. 9 differs from that described with reference to FIGS. 1 to 4 only in the shape of the molded body and the arrangement of the means of communication between the two downstream compartments 55 and 49 of the enclosure and it is therefore needless to describe them in further detail. It operates in identical fashion.

FIGS. 6 to 8 illustrate one embodiment of the invention which is of particularly easy to assemble and manufacture. In order to facilitate an understanding of the description, identical or similar parts bear the same reference numbers in FIGS. 6 to 8 and FIGS. 1 to 4.

Referring more particularly to FIG. 6, there can be noted the essential elements of the arrangement of FIG. 2, in particular the passages 30, 32, the stationary contact 46, the compartments 49, 53 and 55 and the moving contact bearing the piston 48 and the nozzle 50. The body or housing 122 of the apparatus which is of generally parallelepiped shape (see FIGS. 7 and 8) has three subdivisions 128, 130, 132 defined by transverse partitions or webs 124 and 126 and of square section which are capable of serving as recess for the three poles of the circuit breaker. In the central portion of the recess or enclosure of the pole there is mounted a blowout assembly designated by the reference number 134 and formed by a cylinder 136 the end 138 of which is fastened by screwing advantageously to the passage conductor 30 and a piston 48 adapted to slide within the cylinder 136. The unit 134 defines the compression compartment 53 of variable volume ans its cross section corresponds to that of the recess 128 of square cross section of the housing 122 to permit easy insertion with small amount of play. At the four corners of the recess 128 there are defined spaces between the outer surface of the cylinder 136 and the inner wall of the recess 128 which provide communication between the downstream compartment and the dead compartment 49 which are located on opposite sides of the unit 134. Communication through the hollow movable contact therefore proves superfluous in this embodiment. The transverse webs 124 and 126 are provided at the downstream compartments 55 with openings 70 providing communication, in the manner described above, for the enclosures 128, 130 and 132 of the different poles.

The operation of the apparatus shown in FIGS. 6 to 8 does not differ from that described above, and it is sufficient to state this embodiment makes it possible to be independent of the precision of molding of the housing 122, the periphery of the piston 48 no longer cooperating with the wall of the enclosure, but rather with an attached cylinder the manufacture and mounting of which with the required precision do not raise any particular problem. The honeycomb structure of the body of the apparatus imparts to it substantial rigidity and strength, permitting relatively small wall thicknesses and therefore a minimum cost of manufacture.

Although the arrangement in a row of the different poles seems most advantageous, one could imagine poles placed at the vertex of a triangle or in any other manner depending on the number of pole units in the circuit interrupter. The external shape of the housing may, of course, be different, for instance oval, as may be structure of the pole units of the circuit interrupter, without thereby going beyond the scope of the invention.

What is claimed is:

1. A multiphase puffer-type circuit interrupter comprising a gastight enclosure of insulating material defining a plurality of contiguous, generally tube-shaped parallelly extending arcextinguishing chambers, one for each phase, each chamber containing an arc-extinguishing gas; a pair of aligned elongated contact members separable to draw an are between the end portions thereof; a blast orifice surrounding at least one of said end portions; and puffer means to direct a blast of arcextinguishing gas through said blast orifice towards said are upon separation of said contact members, said enclosure including means establishing a direct fluid communication between the exhaust parts of said arc-extinguishing chambers located at the exhaust end of said blast orifice to permit the blast of arc-extinguishing gas of a given chamber to exhaust also into other chambers thereby to put the total volume of the exhaust parts of all chambers at the disposal of each phase.

2. A circuit interrupter according to claim 1. said contact members comprising a hollow contact member defining an inner exhaust conduit.

3. A circuit interrupter according to claim 2, each chamber comprising a further exhaust volume, said further exhaust volume consisting ofa dead space in free fluid communication with said inner exhaust conduit of said hollow contact member.

4. A circuit interrupter according to claim 3, each chamber further comprising a fixed transverse partition wall surrounding said hollow contact member and separating said dead space from a pressure chamber, said puffer means comprising a puffer piston slidably mounted in said pressure chamber.

5. A circuit interrupter according to claim 4, said puffer piston and said blast orifice being'movable with said hollow contact member.

6. A circuit interrupter according to claim 5, said hollow contact member being connected to an outer control rod by a portion of insulating material located in said dead space.

7. A circuit interrupter according to claim 5, said gastight enclosure defining in each chamber a cylindrical portion cooperating in slidable relation with the circumference of said puffer piston to produce said gas blast.

8. A circuit interrupter according to claim 5, said puffer means comprising a puffer cylinder coaxially mounted in the corresponding arc-extinguishing chamber and secured to the inner wall portion of said enclosure.

9. A three-phase puffer-type circuit interrupter comprising a gastight molded enclosure of insulating material having an outer wall member and a pair of inner partition walls defining three generally cylindrical parallelly extending arc-extinguishing chambers containing an arc-extinguishing gas under pressure above atmospheric pressure, each chamber including a pair of axial contact members separable to draw an arc; a blast orifice surrounding at least one end portion of at least one of said contact members; and puffer means to direct a blast of arc-extinguishing gas through said blast orifice towards said are upon separation of said contact members, said partition walls defining orifice means establishing a free fluid communication between the corresponding chambers at the exhaust end of said blast orifices.

10. A multiphase puffer-type circuit interrupter comprising a plurality of juxtaposed elongated parallelly extending arcextinguishing chambers, one for each'phase, each chamber comprising a generally cylindrical envelope of insulating material and containing an arc-extinguishing gas under pressure above atmospheric pressure; a pair of axially aligned elongated contact members separable to draw an are between the end portions thereof; a blast orifice surrounding the end portions of said contact members in the closed-circuit positions thereof; and puffer means to direct a blast of arc-extinguishing gas through said blast orifice towards said are upon separation of said contact members, and transverse conduit means interconnecting in free fluid communication the end portions of said chambers facing the exhaust end of said blast orifices.

11. A circuit interrupter according to claim 10, said transverse conduit means comprising control rod means to simultaneously control the movement of separation of the contact members of said chambers.

12. A puffer-type circuit interrupter comprising:

a. a generally tubular arc-extinguishing chamber containing an arc extinguishing gas,

b. a pair of contact members axially disposed inside said chamber and at least one of which is movable to draw an are between the end portions of said contact members,

c. a puffer mechanism comprising a puffer piston slidably mounted within a cylindrical wall portion of said chamber to produce a blast of arc-extinguishing gas,

3,641,295 9 all d. fixed blast orifice means surrounding at least one of said with respect to said blast orifice means thereby to cause a end portions to guide said blast of gas against said are and part of the gas exhausted from said blast orifice means to adapted to divide said chamber in two Compartments: an circulate backwards through said hollow control rods and upstream compartment comprising said cylindrical wall to attain said back portion. ortion and a d n tream m ent t th exhaust 13. A circuit interrupter according to claim 12. said movaside of said blast orifice means, ble contact member comprising an inner conduit to exhaust a e. a plurality of peripherally disposed, movable hollow conpart of the gas exhausted by said blast orifice means through trol rods slidably traversing said blast orifice means and Sald Inner corldult salfl flownstream compartment connecting said puffer piston to said movable contact p Clrcu" mierruptef aficordmg Claim b i d i i relation, l0 comprising a plurality of ad acent similar arc-extinguishing f. said hollow control rods traversing said piston to establish chamber? f communwanon means estabhshmg free fluid a fl id communication between Said downstream communication between the downstream compartments of partment and the back portion of said upstream compartchambersment located at the opposite side of said puffer piston 

1. A multiphase puffer-type circuit interrupter comprising a gastight enclosure of insulating material defining a plurality of contiguous, generally tube-shaped parallelly extending arcextinguishing chambers, one for each phase, each chamber containing an arc-extinguishing gas; a pair of aligned elongated contact members separable to draw an arc between the end portions thereof; a blast orifice surrounding at least one of said end portions; and puffer means to direct a blast of arc-extinguishing gas through said blast orifice towards said arc upon separation of said contact members, said enclosure including means establishing a direct fluid communication between the exhaust parts of said arc-extinguishing chambers located at the exhaust end of said blast orifice to permit the blast of arcextinguishing gas of a given chamber to exhaust also into other chambers thereby to put the total volume of the exhaust parts of all chambers at the disposal of each phase.
 2. A circuit interrupter according to claim 1, said contact members comprising a hollow contact member defining an inner exhaust conduit.
 3. A circuit interrupter according to claim 2, each chamber comprising a further exhaust volume, said further exhaust volume consisting of a dead space in free fluid communication with said inner exhaust conduit of said hollow contact member.
 4. A circuit interrupter according to claim 3, each chamber further comprising a fixed transverse partition wall surrounding said hollow contact member and separating said dead space from a pressure chamber, said puffer means comprising a puffer piston slidably mounted in said pressure chamber.
 5. A circuit interrupter according to claim 4, said puffer piston and said blast orifice being movable with said hollow contact member.
 6. A circuit interrupter according to claim 5, said hollow contact member being connected to an outer control rod by a portion of insulating material located in said dead space.
 7. A circuit interrupter according to claim 5, said gastight enclosure defining in each chamber a cylindrical portion cooperating in slidable relation with the circumference oF said puffer piston to produce said gas blast.
 8. A circuit interrupter according to claim 5, said puffer means comprising a puffer cylinder coaxially mounted in the corresponding arc-extinguishing chamber and secured to the inner wall portion of said enclosure.
 9. A three-phase puffer-type circuit interrupter comprising a gastight molded enclosure of insulating material having an outer wall member and a pair of inner partition walls defining three generally cylindrical parallelly extending arc-extinguishing chambers containing an arc-extinguishing gas under pressure above atmospheric pressure, each chamber including a pair of axial contact members separable to draw an arc; a blast orifice surrounding at least one end portion of at least one of said contact members; and puffer means to direct a blast of arc-extinguishing gas through said blast orifice towards said arc upon separation of said contact members, said partition walls defining orifice means establishing a free fluid communication between the corresponding chambers at the exhaust end of said blast orifices.
 10. A multiphase puffer-type circuit interrupter comprising a plurality of juxtaposed elongated parallelly extending arc-extinguishing chambers, one for each phase, each chamber comprising a generally cylindrical envelope of insulating material and containing an arc-extinguishing gas under pressure above atmospheric pressure; a pair of axially aligned elongated contact members separable to draw an arc between the end portions thereof; a blast orifice surrounding the end portions of said contact members in the closed-circuit positions thereof; and puffer means to direct a blast of arc-extinguishing gas through said blast orifice towards said arc upon separation of said contact members, and transverse conduit means interconnecting in free fluid communication the end portions of said chambers facing the exhaust end of said blast orifices.
 11. A circuit interrupter according to claim 10, said transverse conduit means comprising control rod means to simultaneously control the movement of separation of the contact members of said chambers.
 12. A puffer-type circuit interrupter comprising: a. a generally tubular arc-extinguishing chamber containing an arc extinguishing gas, b. a pair of contact members axially disposed inside said chamber and at least one of which is movable to draw an arc between the end portions of said contact members, c. a puffer mechanism comprising a puffer piston slidably mounted within a cylindrical wall portion of said chamber to produce a blast of arc-extinguishing gas, d. fixed blast orifice means surrounding at least one of said end portions to guide said blast of gas against said arc and adapted to divide said chamber in two compartments: an upstream compartment comprising said cylindrical wall portion and a downstream compartment at the exhaust side of said blast orifice means, e. a plurality of peripherally disposed, movable hollow control rods slidably traversing said blast orifice means and connecting said puffer piston to said movable contact member in driving relation, f. said hollow control rods traversing said piston to establish a fluid communication between said downstream compartment and the back portion of said upstream compartment located at the opposite side of said puffer piston with respect to said blast orifice means thereby to cause a part of the gas exhausted from said blast orifice means to circulate backwards through said hollow control rods and to attain said back portion.
 13. A circuit interrupter according to claim 12, said movable contact member comprising an inner conduit to exhaust a part of the gas exhausted by said blast orifice means through said inner conduit into said downstream compartment.
 14. A multiphase circuit interrupter according to claim 12, comprising a plurality of adjacent similar arc-extinguishing chambers, and communication means establishing a free fluid communication between the downstream cOmpartments of said chambers. 